The invention relates to the field of rechargeable battery technology and more specifically to rechargeable lithium-ion battery technology.
Among various types of secondary batteries, the lithium-ion battery (LIB) is an environmentally-friendly energy storage device that has a relatively high energy density and excellent cycle life. Lithium-ion battery technology generally uses graphite material for the anode and a metallic oxide material such as LiCoO2 for the cathode.
Though graphite has been primarily used as the active material for the anode of the lithium-ion battery, its small specific capacity (372 milliamp-hours per gram) has limitations to next-generation applications that require a high energy density. Moreover, graphite also has a low transport rate and a corresponding low power density. Therefore, the graphite anode is not considered a promising solution to the battery applications that require both high capacity and power density.
In order to overcome the limitations, there have been significant efforts made to develop advanced anode and cathode materials. For example, high-capacity anode materials such as metal oxides and lithium alloys have been considered to substitute graphite. For the active material, transition metal oxides (TMO) including Co3O4, Fe2O3, NiO, CuO, and TiO2 can be used. For example, some of the aforementioned oxide materials can insert and tally at least six lithium ions per chemical formula, showing a larger reversible capacity than that of graphite material. Such transition metal oxides react with lithium ions during the first discharging and form Li2O and follow a conversion reaction mechanism that reversibly come back to the initial state during the charging process.
However, these materials also show several problems. Some TMO's have poor capacity retention during lithium-ion insertion/extraction and poor rate capability, resulting in severe volume expansion. It is well known that the architectures of transition metal oxide and structure of current collector considerably influence electrochemical performance.
Therefore, there is a need for an improved lithium-ion battery having improved energy and power capabilities.